Re: [PATCH/WIP 4/8] am: split out mbox/maildir patches with git-mailsplit

git-am.sh supports mbox, stgit and mercurial patches. Re-implement
support for splitting out mbox/maildirs using git-mailsplit, while also
implementing the framework required to support other patch formats in
the future.

Re-implement support for the --patch-format option (since a5a6755
(git-am foreign patch support: introduce patch_format, 2009-05-27)) to
allow the user to choose between the different patch formats.

Signed-off-by: Paul Tan <redacted>
---

@@ -128,13 +190,32 @@ static void am_next(struct am_state *state)
  */
+/**
+ * parse_options() callback that validates and sets opt->value to the
+ * PATCH_FORMAT_* enum value corresponding to `arg`.
+ */
+static int parse_opt_patchformat(const struct option *opt, const char *arg, int unset)
+{
+       int *opt_value = opt->value;
+
+       if (!strcmp(arg, "mbox"))
+               *opt_value = PATCH_FORMAT_MBOX;
+       else
+               return -1;
+       return 0;
+}
+
 struct am_state state;
+int opt_patch_format;